Conventionally, in the case of handling a plurality of sheets of images, an image registration process has become a necessary technique for establishing positional correspondence between the images, as the foundation of image processing techniques. For example, in the case of executing an image mosaicing process (a process which executes registration of a plurality of images having overlaps and obtains one whole image) and a super resolution process, it is necessary to execute a synthesizing process of a plurality of sheets of images. If there is an error in the registration process of the images used at the time of the synthesis process, the synthesis process fails and a desired image processing result can not be obtained.
For example, an image super resolution process is proposed as an image-resolution increasing technique using a plurality of sheets of images (refer to WO06/052029).
In recent years, as for methods to detect registration errors in the case where an image registration process is executed, several reports are reported as in the following:    (1) Chang, Shimizu, and Okutomi, “Two Steps Registration of Area Selection Registration Robust to Lighting Change and Occlusion”, Speech Thesis Collection for Meeting on Image Recognition and Understanding (MIRU2006), Jul., 2006, p. 229-234; and    (2) Toda, Tsukada, and Inoue, “Super Resolution Process in Consideration of Registration Error”, Speech Thesis Collection for 5th Forum on Information and Technology (FIT2006), 2006, p. 63-64.